The present invention relates to anti-theft alarms and, more particularly, to an alarm designed to prevent the theft of articles of unattended personal property such as handbags, attache cases, suit cases, or the like.
Articles of personal property, such as handbags and attache cases, are often left temporarily unattended at a location in a business establishment while the proprietor thereof is attending to duties at a location remote from the site of the article of personal property. For instance, secretaries often leave their handbags unattended at their desks while retrieving files or taking dictation at other locations within the business establishment. This situation presents an opportunity for other employees or persons who have gained entry to the business establishment either through authorized or unauthorized means to secure possession of the handbag and leave the premises or conceal the stolen item before the theft is discovered.
There have been a number of attempts to design alarms to prevent the theft of articles of personal property in instances such as described above. However, these alarms suffer from the common disadvantages of being bulky, heavy, complex, expensive and relatively insensitive, which are inherent in the use of the various types of mechanical trigger devices which are employed therein. Some alarms utilize mechanical trigger devices connected to the handle of the article of personal property such that the grasping of the handle actuates the alarm. However, if the article of personal property is lifted without using the handle, such an alarm is ineffective. Other mechanical trigger mechanisms are connected to the handbag clasp and thus are not actuated unless the handbag is opened. Still other trigger means are connected to the carrying strap and thus are not actuated unless the bag is pulled from the owner while the owner is holding the strap.
Another type of trigger mechanism incorporates a switch with a depressible elongated actuator which normally protrudes from the bottom of the handbag and is held in a depressed position by the weight thereof. When the handbag is lifted from the surface upon which it rests, the elongated actuator, which is springloaded, becomes extended, thereby actuating the alarm. This design is disadvantageous because it requires an aperture on the bottom of the handbag through which the elongated actuator can extend. Mechanical triggers have been used which are sensitive to tilting, such as through the use of a rolling ball which will move relative to the remainder of the mechanism when the article is moved. However, devices of this sort are generally rather insensitive and a thief, who is aware of the presence of the alarm, is usually able to manipulate the article of personal property in a manner which will not actuate the alarm as the article of personal property is being stolen.
In order to alleviate the above-mentioned disadvantages, it is possible to replace the mechanical trigger with a low-cost electrical actuator which is extremely sensitive to vibration. However, when this substitution is made, two problems result which must be overcome before a workable alarm is achieved. First, a vibration sensitive electronic switch will require a substantial amount of time after the article of personal property is placed in position and the alarm armed before it reaches mechanical equilibrium. Prior to this time, the mere placing of the article of personal property or the arming of same by turning a key or actuating a switch will set the alarm off due to the sensitivity of the device. Thus, it is necessary that the alarm remain insensitive to motion or vibration for a certain period after the arming thereof. Second, the sensitivity of the alarm must be adjustable so as to prevent the actuation of the alarm by ambient vibration below a given magnitude such as that caused by people walking by or vibrations caused by passing trains, machinery, etc. It is therefore required that the electronic actuator be extremely sensitive to any abnormal vibration or motion and yet be insensitive to ambient vibrations below a certain level.
It is further required that the alarm be compact, light-weight and inexpensive. The objects may be obtained through the utilization of commercially available, integrated circuits utilized in conjunction with an inexpensive electronic actuator, the sensitivity of which can be controlled in a simple manner such that same is insensitive to ambient vibrations below a given magnitude but is extremely sensitive to vibrations or movement above the preset magnitude.
It is, therefore, a prime object of the present invention to provide an alarm for preventing the theft of personal property wherein an electronic actuator is utilized which is sensitive to vibrations or movement.
It is another object of the present invention to provide an alarm for preventing theft of personal property wherein the sensitivity of the electronic actuator can be adjusted so as to render same insensitive to ambient vibrations below a given magnitude.
It is another object of the present invention to provide an alarm for preventing theft of personal property wherein the actuation of the alarm circuitry is prevented for predetermined time after arming of same in order to permit the electronic actuator to achieve mechanical equilibrium.
It is a further object of the present invention to provide an alarm for preventing the theft of personal property wherein an alarm signal is generated through the use of commercially available integrated circuits.
It is still another object of the present invention to provide an alarm for preventing theft of an article of personal property wherein the device is light-weight, small in size, simple and inexpensive to manufacture.